Immunology An Overview

1. Immunology An Overview Learn on your own: Tolerance Clinical Immunology Self-Test Questions: A: 1 B: 1 - 4 C: 1 - 3 D: both E: 1 The only Principle of Immunology for which there is no ambiguity: Every Principle of Immunology has Ambiguity Overview of Immune System

2. Our immune defense has two branches 1. ‘Innate’ defenses First lines of defense Rapid response Defend in a general way -- not pathogen specific Usually sufficient 2. ‘Acquired’ defenses Last line of defense Pathogen specific Creates immunity Slower onset These systems closely interact Respiratory tract cilia of innate defenses Antibody molecule of Acquired defenses Overview of Immune System

3. Four characteristics distinguish Acquired vs Innate responses Overview of Immune System

4. What are the types of Innate Immunity? I. Non-induced mechanisms “Barriers to infection” -- 1st line of defense Anatomical Mechanical Cilia and mucus Skin wounding Overview of Immune System

5. Innate Immunity… II. Induced mechanisms Physiological, e.g., fever Cellular , e.g., phagocytosis Enzymatic, e.g., complement Receptor-mediated Broadly specific -- recognize “danger signals” -- PAMPs Responses phagocytosis pathogen killing antigen presentation cytokine production http://lpi.oregonstate.edu/infocenter/phagocytosis.html Overview of Immune System

6. Microbes can cause infections outside or inside of cells Always Intracellular: Viruses Intra- or extra- cellular: Bacteria Usually extracellular: Fungi, Protozoa, worms Adenovirus infected cell Listeria infected cell Listeria Overview of Immune System

7. There are two “arms” of the Acquired Immune System? Humoral Attack extracellular pathogen and toxins B-cells ------> antibodies Cell-mediated 1) Attack infected body cells & cancerous cells T-killer cells T-cells T-helper cells 2) Hormonal regulation (Cytokines) Overview of Immune System

8. Antibodies are produced by the Humoral arm of the acquired immune system Involves B-cells Attack pathogens outside of cells Have B-cell receptors (BCR) -- a type of antibody Overview of Immune System

9. T-cells possess T-cell Receptors Similar to Antibodies -- antigen-specific -- one type per cell -- created by gene rearrangements However, -- less specific than antibodies -- less diverse (fewer types) -- never are released -- only bind to antigens on MHC Overview of Immune System

10. T-helper cells and T-killer cells bind to different types of MHC Killer-T cells -- bind to AG on MHC-I -- attack infected & cancerous cells Helper-T cells -- bind to AG on MHC-II -- hormonally regulates immune response Macrophages, Dendritic cells, B-cells Overview of Immune System

11. What are the two types of antigen-presenting cells? “Professional” AG-presenting cells “Non-professional” -- via MHC-I or MHC-II -- All nucleated body cells -- can present antigen to TH and TC cells -- only present to Cytotoxic T-cells Examples -- only via MHC-I -- dendritic cells & -- response is cell destruction -- macrophages -- B-cells -- (other IM cells) Overview of Immune System

12. Upon activation Naïve immune cells become Effector cells B-cells become: Plasma cells TH cells become: TH effector cells -- activate other cells Tc cells become: Cytotoxic lymphocytes (CTLs) Overview of Immune System

13. What happens when lymphocytes are activated? “Clonal Selection” Antigen recognition Cell activation Memory cells Immunological memory Primary vs Secondary responses Overview of Immune System

14. How do immune cells communicate? Extensive cell-cell contact Membrane protein interaction Immune synapse Hormonal exchange Cytokines Interleukins Interferons Chemokines etc Endocrine Paracrine Autocrine Overview of Immune System